1. Field of the Invention
The present invention generally relates to a driver of light emitting devices, and more particularly, to a current-type driver of light emitting devices.
2. Description of Related Art
FIG. 1 is a diagram of a conventional voltage-type driver of light emitting devices. Referring to FIG. 1, the conventional voltage-type driver 100 includes a power conversion circuit 102, resistors R1 and R2, and an output capacitor Co. The voltage-type driver 100 divides an output voltage Vout through the resistors R1 and R2 to obtain a feedback signal Vf. The power conversion circuit 102 controls the duty cycle of a pulse width modulation (PWM) signal thereof according to the feedback signal Vf, so as to change the value of the output voltage Vout and provide a stable output voltage Vout to a load 104. In the conventional voltage-type driver 100, even though the output voltage Vout can be adjusted through the feedback signal Vf, the current (i.e., the driving current) output to the load 104 cannot be adjusted. Especially when the load 104 is light emitting diodes (LEDs) that emit light in different colors, the conventional voltage-type driver 100 cannot adjust the output currents supplied to the LEDs according to different characteristics of the LEDs that emit light in different colors. Thus, the conventional voltage-type driver 100 cannot meet the requirement of an actual application when it is applied to LEDs.